Harp seal (Phoca Groenlandica) invasions in north Norwegian coastal waters: A preliminary report on age composition and feeding habits

Abstract

Since 1978 large numbers of harp seals (Phoca groenlandica) have invaded areas of North Norway in winter and spring. In 1987 and 1988 dramatic increases occurred both in magnitude and geographic extent of these seal invasions, and it is suggested that the collapse of the Barents Sea capelin stock in 1985/1986 may have been a contributory factor to this. Sampling of stomach contents for food analyses and of teeth for age determinations was carried out from harp seals taken as bycatch in Norwegian gill-net fisheries in 1986 and 1988. It appears that the seal herds comprised both immature and mature animals. The stomach analyses suggested that feeding was opportunistic, with a variety of fish (in particular the gadoid species cod, saithe, haddock and Norway pout, and the pelagic shoaling species herring and capelin) being taken as prey. Prawns and squid were also consumed, but in considerably lower quantities than fish.